When the time comes to make a baby, a woman may regret her decision to marry Mr. Steady instead of Mr. Sexy.

New research finds that women tend to be more critical of and less attracted to a mate during ovulation if they consider the man to be stable but not that sexy. The study is in the journal Hormones and Behavior.

Researchers asked 108 women to rate their partners by answering questions like: How sexy would women say your partner is compared to most men? And they also asked them to rate the stability and loyalty of their partner.

The subjects’ level of commitment to their relationship remained stable throughout their fertility cycles. But when asked specifically about levels of intimacy and sexual attraction to their mates, there were significant differences.

As they went from low fertility to high fertility, women partnered with less sexy men lowered their attraction ratings. They also found more faults with their stable men.

But women with the most sexually attractive men had precisely the opposite experience.

The authors note that a woman’s feelings for her man can vary day by day. But few probably realize that variations are in part determined by their own fertility hormones.